There has been a technique to control the voltage at a self-terminal position (position where a power system control device is installed) to reach a target voltage using a power system control device, such as a step voltage regulator (SVR) or a static var compensator (SVC).
In addition, a technique which is so-called centralized control technique has been known (PTL 1), in which the overall state of a power system is grasped in a batch by a monitor control server to supply the optimal control instruction to each control device. Another technique for SVR to monitor reactive power is also known (PTL 2), in which when the reactive power is continuously measured for or longer than a predetermined time, it can be estimated that the SVC is in operation, and a tap switching control of the SVR is performed. This technique is so-called autonomous distributed control technique that does not require any communication.